DietPi for VirtualBox:All the great features of DietPi, wrapped up into a lightweight Virtual Machine:
DietPi for VirtualBox allows you to instantly create an optimized and powerful DietPi system. Useful when single-board computers are simply not enough.

Extract the DietPi VirtualBox image:
You can extract the DietPi VirtualBox files anywhere on your system.

Optional: Change CPU core count and available RAM:
Before running the VM, it would be wise to tweak these values for your host system. Once the VM is imported, select it and simply choose settings > system and configure as required.

Run the DietPi VirtualBox Virtual Machine:
Simply double click the DietPi_vXXX_VirtualBox-x64-(Jessie).ova file to launch the virtual machine. If you have less RAM or CPU cores than required, you will receive a prompt which will allow you to change those settings.